1. Field of the Invention
The present invention relates to nylon nucleic acids and nylon polymers that contain pendant nucleosides.
2. Description of the Related Art
In addition to its essential role in life involving the storage and expression of genetic information, the applications of DNA have expanded beyond biology. Owing to its outstanding molecular recognition and self-assembly properties and relatively simple and stable structure, DNA molecules have also been utilized as linkers or templates to assemble many nanostructures (Seeman, 2003) and hetero-species, (Katz et al., 2004) such as fullerenes (An et al., 1996; and Bergamin et al., 2001), nanoparticles (Zheng et al., 2006; and Merkoci et al., 2005; Sato et al., 2007) or carbon nanotubes (Li et al., 2005; Wooley, 2005; Katz et al., 2004; and Zuccheri et al., 2005) and to construct hybrid nanostructures or nanodevices, such as nanowires (Braun et al., 1998; Richter et al., 2001; Woolley, 2003 and Burley et al., 2006), field-effect transistors (Keren et al., 2003), luminescent sensors or electronic sensors (Li et al., 2003; He et al., 2004; Staii et al., 2005; and Briones et al., 2006) and nanomechanical devices (Fritz et al., 2000; Seeman, 2005; and Bath et al., 2007). However, far fewer stereo- and regio-specific DNA-mediated polymer syntheses are known (Datta et al., 2006 and 2008; Kleiner et al. 2008).
Recently, the laboratories of the present inventors have reported the use of DNA as a scaffold for the construction of a nylon-like polymer (Zhu et al., 2002 and 2003). In that study, the 2′ position of an RNA analog nucleoside was derivatized with diamino or dicarboxyl groups; the pendent groups were condensed into a short nylon-like molecule (see the nylon nucleic acid synthesis in FIG. 1). The long-term goal of this work is to use the topological control afforded by nucleic acids (Rothemund et al., 2006; Lund et al., 2006; Seeman, 2005; and Feldkamp et al., 2006) to direct the topology of polymers with industrial importance. In the design of the strands reported in the earlier work from the laboratories of the present inventors, a 16-mer with four nylon nucleic acid residues flanked by polythymidine, 5′-(dT)6UcUnnUccUn(dT)6, was synthesized via single-stranded amide ligation from an uncoupled precursor strand. The notation, which will be used in the specification throughout, indicates uridine nucleotides containing single amino or carboxyl modifications as Un or Uc, respectively, and diamino or dicarboxyl modifications are labeled as Unn or Ucc, respectively (FIG. 2). The coupled products (i.e., nylon nucleic acids) are indicated by an underline at the coupled nucleotides (e.g., UnUc). Thus, the previous nylon nucleic acid was synthesized with only thymidine and modified uridine residues. The disadvantage of an oligonucleotide whose nucleotides consist entirely of rU or dT is that there is no control over the position or manner in which it binds its oligo-dA complement; the possibility of triple helix formation is another confounding factor (Felsenfeld, 1957). To realize nylon polymer synthesis programmed by base pairing, heterobase oligonucleotides or polynucleotides must be utilized.
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